The present invention generally relates to a device, system and method for treating a deformed heart valve. The present invention more particularly relates to a device, system and method for constricting or reforming a mitral valve annulus from within the coronary sinus to correct mitral valve dilation without blocking blood flow in the circumflex artery and which may be implemented using a guide wire within the coronary sinus to effect accurate device deployment and substitution.
The human heart generally includes four valves. Of these valves, a most critical one is known as the mitral valve. The mitral valve is located in the left atrial ventricular opening between the left atrium and left ventricle. The mitral valve is intended to prevent regurgitation of blood from the left ventricle into the left atrium when the left ventricle contracts. In preventing blood regurgitation the mitral valve must be able to withstand considerable back pressure as the left ventricle contracts.
The valve cusps of the mitral valve are anchored to muscular wall of the heart by delicate but strong fibrous cords in order to support the cusps during left ventricular contraction. In a healthy mitral valve, the geometry of the mitral valve ensures that the cusps overlie each other to preclude regurgitation of the blood during left ventricular contraction.
The normal functioning of the mitral valve in preventing regurgitation can be impaired by dilated cardiomyopathy caused by disease or certain natural defects. For example, certain diseases may cause dilation of the mitral valve annulus. This can result in deformation of the mitral valve geometry to cause ineffective closure of the mitral valve during left ventricular contraction. Such ineffective closure results in leakage through the mitral valve and regurgitation. Diseases such as bacterial inflammations of the heart or heart failure can cause the aforementioned distortion or dilation of the mitral valve annulus. Needless to say, mitral valve regurgitation must not go uncorrected.
One method of repairing a mitral valve having impaired function is to completely replace the valve. This method has been found to be particularly suitable for replacing a mitral valve when one of the cusps has been severely damaged or deformed. While the replacement of the entire valve eliminates the immediate problem associated with a dilated mitral valve annulus, presently available prosthetic heart valves do not possess the same durability as natural heart valves.
Various other surgical procedures have been developed to correct the deformation of the mitral valve annulus and thus retain the intact natural heart valve function. These surgical techniques involve repairing the shape of the dilated or deformed valve annulus. Such techniques, generally known as annuloplasty, require surgically restricting the valve annulus to minimize dilation. Here, a prosthesis is typically sutured about the base of the valve leaflets to reshape the valve annulus and restrict the movement of the valve annulus during the opening and closing of the mitral valve.
Many different types of prostheses have been developed for use in such surgery. In general, prostheses are annular or partially annular shaped members which fit about the base of the valve annulus. The annular or partially annular shaped members may be formed from a rigid material, such as a metal, or from a flexible material.
While the prior art methods mentioned above have been able to achieve some success in treating mitral regurgitation, they have not been without problems and potential adverse consequences. For example, these procedures require open heart surgery. Such procedures are expensive, are extremely invasive requiring considerable recovery time, and pose the concomitant mortality risks associated with such procedures. Moreover, such open heart procedures are particularly stressful on patients with a comprised cardiac condition. Given these factors, such procedures are often reserved as a last resort and hence are employed late in the mitral regurgitation progression. Further, the effectiveness of such procedures is difficult to assess during the procedure and may not be known until a much later time. Hence, the ability to make adjustments to or changes in the prostheses to obtain optimum effectiveness is extremely limited. Later corrections, if made at all, require still another open heart surgery.
An improved therapy to treat mitral regurgitation without resorting to open heart surgery has recently been proposed. This is rendered possible by the realization that the coronary sinus of a heart is near to and at least partially encircles the mitral valve annulus and then extends into a venous system including the great cardiac vein. As used herein, the term xe2x80x9ccoronary sinusxe2x80x9d is meant to refer to not only the coronary sinus itself but in addition, the venous system associated with the coronary sinus including the great cardiac vein. The therapy contemplates the use of a device introduced into the coronary sinus to reshape and advantageously effect the geometry of the mitral valve annulus.
The device includes a resilient member having a cross sectional dimension for being received within the coronary sinus of the heart and a longitudinal dimension having an unstressed arched configuration when placed in the coronary sinus. The device partially encircles and exerts an inward pressure on the mitral valve. The inward pressure constricts the mitral valve annulus or at least a portion of it to essentially restore the mitral valve geometry. This promotes effective valve sealing action and eliminates mitral regurgitation.
The device may be implanted in the coronary sinus using only percutaneous techniques similar to the techniques used to implant cardiac leads such as pacemaker leads. The device is implanted using an elongated introducer configured for being releasably coupled to the device. The introducer is preferably flexible to permit it to advance the device into the heart and into the coronary sinus through the coronary sinus ostium. To promote guidance, an elongated sheath is first advanced into the coronary sinus. Then, the device and introducer are moved through a lumen of the sheath until the device is in position within the coronary sinus. Because the device is formed of resilient material, it conforms to the curvatures of the lumen as it is advanced through the sheath. The sheath is then partially retracted to permit the device to assume its unstressed arched configuration. Once the device is properly positioned, the introducer is then decoupled from the device and retracted through the sheath. The procedure is then completed by the retraction of the sheath. As a result, the device is left within the coronary sinus to exert the inward pressure on the mitral valve to restore mitral valve geometry.
The foregoing therapy has many advantages over the traditional open heart surgery approach. Since the device, system and method may be employed in a comparatively noninvasive procedure, mitral valve regurgitation may be treated at an early stage in the mitral regurgitation progression. Further, the device may be placed with relative ease by any minimally invasive cardiologist. Still further, since the heart remains completely intact throughout the procedure, the effectiveness of the procedure may be readily determined. Moreover, should adjustments be deemed desirable, such adjustments may be made during the procedure and before the patient is sent to recovery.
Unfortunately, the human anatomy does impose some obstacles to this recently proposed procedure for treating mitral regurgitation. More specifically, the human heart includes a coronary artery which descends from the aorta. One branch of the coronary artery is the circumflex artery which, in turn, includes the left marginal branch of the circumflex artery. As used herein, the term xe2x80x9ccircumflex arteryxe2x80x9d is taken to include the circumflex artery itself or any branch therefrom. The circumflex artery extends distally generally along the coronary sinus but at a point proximal to the coronary artery, it passes under the coronary sinus. The circumflex artery supports blood flow important to the viability of the heart. Hence, reduction in this blood flow must be avoided. As a result, a device placed in the coronary sinus must not be permitted to extend within the coronary sinus beyond the crossover point of the circumflex artery and the coronary sinus to avoid constriction of the circumflex artery. This contemplates the need to know the location of the circumflex artery and coronary sinus crossover point. It also contemplates accurate positioning of the device within the coronary sinus to assure that the device does not extend over the circumflex artery.
The above is further compounded by the fact that the human heart anatomy and indeed the mitral valve condition will vary from patient to patient. Hence, after deployment of an initial therapy device, the initial device effectiveness must be tested. Should a further device having different properties or configuration be deemed more efficacious, there must be provided a way to easily remove the initial device and then deploy the further device with the same deployment accuracy to avoid the crossover of the circumflex artery with the coronary sinus.
The present invention addresses these issues. The present invention provides a therapy system and procedure which enables avoidance of the crossover of the circumflex artery with the coronary sinus by permitting accurate placement of an initial device or any substitute device within the coronary sinus. Further to that end, the present invention enables the crossover point of the circumflex artery with the coronary sinus to be readily determined and, if desired, continuously observed during the therapy procedure. Still further, the present invention contemplates a mitral valve therapy device which is configured to avoid constricting the circumflex artery even though it passes over the circumflex artery within the coronary sinus.
The present invention provides an assembly for effecting the condition of a mitral valve annulus of a heart. The assembly includes a guide wire configured to be fed into the coronary sinus of the heart and a mitral valve annulus therapy device configured to be slidably received on the guide wire and advanced into the coronary sinus of the heart on the guide wire.
The assembly may further include an elongated introducer configured to be slidingly received on the guide wire proximal to the device. The introducer may be releasably locked to the device during the deployment of the device within the coronary sinus. The assembly may further include a guide tube having an inner lumen dimensioned for receiving the guide wire and the device and introducer when the device and introducer are slidingly received on the guide wire.
The assembly may still further include an elongated flexible member which is visible under X ray fluoroscopy and which may be advanced into the circumflex artery. The guide wire may also be visible under X ray fluoroscopy to reveal, under X ray fluoroscopic examination, the crossover point of the circumflex artery and the coronary sinus.
The present invention still further provides a mitral valve annulus device for reshaping the mitral valve annulus to effect the condition of a mitral valve annulus of a heart. The device includes a resilient member having a cross sectional dimension for being received within the coronary sinus of a heart and having a longitudinal dimension having an arched configuration for partially encircling the mitral valve and exerting an inward pressure on the mitral valve when within the coronary sinus adjacent the mitral valve for reshaping at least a portion of the mitral valve annulus. The device includes a distal end having a bent portion to avoid exerting pressure on the circumflex artery at the crossover point of the circumflex artery and the coronary sinus.
The present invention further provides a mitral valve annulus therapy device including a generally C-shaped clip member formed of resilient material for exerting a substantially radially inward force on the mitral valve annulus when placed in the coronary sinus of a heart about and adjacent to the mitral valve. The device has a distal end including a bent portion to avoid exerting pressure on the circumflex artery at the crossover point of the circumflex artery and the coronary sinus.
The present invention further provides a method of determining the crossover point of the circumflex artery and coronary sinus of a heart. The method includes the steps of inserting a first elongated flexible rod into the coronary sinus, the first rod being visible under X ray fluoroscopy, inserting a second elongated flexible rod into the circumflex artery, the second rod being visible under X ray fluoroscopy, and subjecting the heart to X ray fluoroscopic examination to determine the crossover point of the first and second rods.
The present invention further provides a method of deploying a mitral valve annulus reshaping device within the coronary sinus of a heart. The method includes the steps of inserting a guide wire into the coronary sinus of the heart, and advancing an elongated mitral valve annulus constricting device on the guide wire and into the coronary sinus into a position such that the device at least partially encircles the mitral valve of the heart.
The advancing step may further include the steps of slidingly mounting an elongated flexible introducer onto the guide wire proximal to the device, engaging the distal end of the introducer with the proximal end of the device, and pushing the device distally into the coronary sinus with the introducer. After the device is deployed in the coronary sinus, the introducer may be withdrawn.
During deployment of the device, the introducer may be releasably locked to the device. After deployment, but before the introducer is withdrawn, the introducer may be released from the device.
The method may further include the steps of providing an elongated flexible guide tube having an inner lumen, the inner lumen having a cross sectional dimension greater than the cross sectional dimension of the guide wire, and feeding the guide tube into the coronary sinus of the heart over the guide wire with the guide wire within the inner lumen of the guide tube. Thereafter, the device may be pushed along the guide wire and within the guide tube.
The present invention further provides a method of deploying a mitral valve annulus therapy device within the coronary sinus of a heart. The method includes the steps of inserting a first wire into the circumflex artery of the heart, the first wire being visible under X ray fluoroscopy, inserting a second wire into the coronary sinus of the heart, the second wire being visible under X ray fluoroscopy, subjecting the heart to X ray fluoroscopic examination to visualize the crossover point of the first and second wires, and deploying an elongated mitral valve annulus therapy device within the coronary sinus in a position such that the distal end of the device is proximal to the crossover point of the first and second wires. Preferably, during deployment, the device is guided by the second wire into the coronary sinus.
The method may further include the steps of slidingly mounting an elongated flexible introducer onto the second wire proximal to the device, engaging the distal end of the introducer with the proximal end of the device, and pushing the device distally into the coronary sinus with the introducer. During deployment, the introducer may be releasably locked to the device. After deployment, the introducer may be released from the device and withdrawn.
The method may further include the steps of providing an elongated flexible guide tube having an inner lumen, the inner lumen having a cross sectional dimension greater than the cross sectional dimension of the second wire, and the guide tube being transparent to X ray fluoroscopy, and feeding the guide tube into the coronary sinus of the heart over the second wire with the second wire within the inner lumen of the guide tube. The device may then be pushed along the second wire by the introducer and within the guide tube until it reaches a desired position within the coronary sinus.
The present invention still further provides a method of deploying a constricting device within the coronary sinus of a heart to reshape the mitral valve annulus of the heart. The method includes the steps of providing an elongated flexible guide wire having a cross sectional dimension, feeding the guide wire into the coronary sinus of the heart, providing an elongated flexible guide tube having an inner lumen, the inner lumen having a cross sectional dimension greater than the cross sectional dimension of the guide wire, and feeding the guide tube into the coronary sinus of the heart over the guide wire with the guide wire within the inner lumen of the guide tube.
The method further includes the steps of providing a mitral valve annulus constricting device configured to be slidingly received on the guide wire and within the inner lumen of the guide tube, the device including a proximal end, providing a flexible elongated introducer configured to be slidingly received on the guide wire and within the inner lumen of the guide tube, the introducer having a distal end, and placing the device onto the guide wire.
The method still further includes the steps of placing the introducer onto the guide wire, engaging the distal end of the introducer with the proximal end of the device, pushing the device with the introducer in a distal direction along the guide wire and within the guide tube until the device is at least partially encircling the mitral valve within the coronary sinus of the heart, and withdrawing the introducer and the guide tube from the heart.
During deployment of the device, the introducer may be releasably locked to the device. After deployment, but before the introducer is withdrawn, the introducer may be released from the device. The effectiveness of the device may then be tested.
Should a replacement device be required, further steps to replace the device with a substitute device may be taken. Those steps may include feeding the guide tube into the coronary sinus of the heart over the guide wire and the device, feeding the introducer over the guide wire and into the guide tube, releasably locking the distal end of the introducer to the proximal end of the device, and retracting the introducer and device in a proximal direction and from the guide tube. When the device has been removed, a replacement device may then be deployed in the same manner as the initial device was deployed.